1. Field of the Invention
This invention relates to superhard polycrystalline cutting elements used for wear, drawing and other tool applications where superhard properties are useful. More specifically, this invention relates to such superhard polycrystalline cutting elements that make use of polycrystalline diamond regions for the cutting or wear surface.
2. Description of Related Art
A wide variety of polycrystalline diamond compacts (PDC) are well known in the art. Generally, these prior devices do not incorporate a thermally stable catalytic element in the region adjacent to the cutting surface, that therefore prior PDC devices tend to have a mismatch in thermal expansion that can cause the interstitial metal to exert a high stress on the diamond lattice, which in turn can lead to fracture of the diamond-to-diamond bonds and subsequent premature failure of the compact. Further, prior PDC devices tend to incorporate a non-thermally stable catalytic element that readily dissolves carbon from the diamond surface at elevated temperatures, thereby, leading to the conversion of diamond to graphite, which in turn leads to premature failure of the compact.
Common PDCs are formed by subjecting diamond or other superhard particles (such as Cubic Boron Nitride (CBN) and the like) to high-temperatures and high pressure in the presence of a metallic catalyst to form a polycrystalline matrix of inter-bonded particles. This bonding process is typically referred to as “sintering.” The metallic catalyst typically remains in the polycrystalline diamond matrix, although some PDCs have used leaching to remove some or all of the catalyst. Well known PolyCrystalline Diamond (PCD) elements typically consist of a facing table of polycrystalline diamond integrally bonded to a substrate of a less hard material, such as cemented tungsten carbide. This material is often referred to as a Polycrystalline Diamond Compact (PDC). PDC is commonly used in down hole tools; such as drill bits (including drag bits, also called fixed cutter bits; percussion bits; rolling cone bits, also called rock bits), reamers, stabilizers and tool joints.
Thermal stability in a PDC has become known as important for its relationship to the successful use of the compact's use in hard rock drilling applications. High temperatures are generated at the leading edge of the PDC tool while cutting rock. These high temperatures can cause premature failure of the tool via several mechanisms, two of which are graphitization of the polycrystalline diamond in contact with the interstitial metallic catalyst and thermal expansion of the interstitial metallic catalyst. In the graphitization mechanism, carbon is readily dissolved from the diamond surface as the temperature of the cutting tip increases above about 450° C. This dissolving of the carbon is due to the increased saturation level of carbon in the metallic catalyst with increasing temperature. The dissolved carbon takes the form of graphite since the PCD tool operates outside of the thermodynamic stability region of diamond. In the thermal expansion mechanism, this thermal expansion of the metallic catalyst is several times greater than that of diamond for a given increase in temperature. The mismatch in thermal expansion causes the interstitial metal to exert a high stress on the diamond lattice. These stresses can lead to a fracture of diamond-to-diamond bonds at or above about 700° C. and subsequent premature failure of the compact.
The most common method of improving the thermal stability of PDC is to fully or partially remove the metallic catalyst from the diamond lattice. Some of the following listed references disclose this technique in some detail. Material with the metallic catalyst removed from the entire sintered diamond body is commonly known as Thermally Stable Polycrystalline (TSP) diamond.
Although the following references may not necessarily qualify as “prior art,” the reader is referred to these following U.S. Patent documents for general background material. Each of these patent references is hereby incorporated by reference in its entirety for the material contained therein.
U.S. Pat. No. 3,745,623 describes diamond tools and superpressure processes for the preparation thereof, wherein the diamond content is present either in the form of a mass comprising diamond crystals bonded to each other or of a thin skin of diamond crystals bonded to each other.
U.S. Pat. No. 4,224,380 describes a compact for tools, such as cutting, drilling and shaping tools that consists essentially of self-bonded abrasive particles.
U.S. Pat. No. 4,311,490 describes a process for preparing a composite compact wherein a mass of abrasive crystals, a mass of metal carbide, and a boding medium are subjected to a high-temperature/high pressure process for providing a composite compact.
U.S. Pat. No. 4,333,986 describes a diamond sintered compact wherein diamond crystal particles are uniformly oriented in a particular direction and the method for producing the same.
U.S. Pat. No. 4,518,659 describes a high pressure/high temperature catalyst sweep through process for making diamond and cubic boron nitride compacts that adds an intermediate metal or metal alloy.
U.S. Pat. No. 4,525,179 describes a high pressure/high temperature (HP/HT) process for making diamond or CBN compacts that includes placing partitions within the crystal mass before HP/HT processing.
U.S. Pat. No. 4,629,373 describes a polycrystalline diamond body with a plurality of faces having enhanced surface irregularities over at least a portion of at least one of the faces.
U.S. Pat. No. 4,664,705 describes a polycrystalline diamond (PCD) body with improved thermal stability which comprises a PCD body which has had at least one of its previously empty pores infiltrated by a silicon containing alloy.
U.S. Pat. No. 4,694,918 describes a percussion rock bit that comprises a steel body having a means for connection to a drill string at one end and having a plurality of inserts at the other end for crushing rock at the bottom of a hole being drilled.
U.S. Pat. No. 4,738,689 describes a polycrystalline compact of self-bonded diamond particles having a network of interconnected empty pores dispersed throughout.
U.S. Pat. No. 4,798,026 describes a thermostable abrasive diamond product that includes a compact formed of diamond grains representing more than 80% by volume of the compact, each grain being bonded directly to its neighbors so as to form a polycrystalline structure.
U.S. Pat. No. 4,871,377 describes a composite compact adapted for high-temperature uses, such as a cutter on a rotary drill bit, which includes a relatively thick table of diamond or boron nitride particles with a strong, chemically inert binder matrix and a thin metal layer bonded directly to the table in a HP/HT press.
U.S. Pat. No. 4,874,398 describes a process for producing a diamond compact having a compressive strength of at least 10 kbars.
U.S. Pat. No. 4,906,528 describes a cutting element of flat shape suitable for use as a drill tip that comprises a central abrading blade containing more than 80% vol. CBN sandwiched between two lateral support layers.
U.S. Pat. No. 4,948,388 describes a diamond compact comprised of 60-95 volume percent of diamond crystals which have been plastically deformed so that they form a rigid framework structure in which contacts between the diamond crystals occur over surfaces arising from plastic deformation of the diamond crystals during formation of the compact under pressure and temperature conditions within the graphite stability field.
U.S. Pat. No. 4,985,051 describes a diamond compact composed of 60-95 volume % diamond crystals plastically deformed into a closely packed, rigid structure with contacts between the diamond crystals over extended mating surfaces arising from the plastic deformation.
U.S. Pat. No. 5,009,673 describes a method for manufacturing a polycrystalline sandwich compact comprising a polycrystalline diamond or CBN core interposed between outer support layers.
U.S. Pat. No. 5,011,509 describes a compact blank for use in operations that require very high abrasion resistance and a thermally stable cutting edge.
U.S. Pat. No. 5,011,514 describes superabrasive cutting elements, backed compacts and methods for their manufacture wherein metal-coated superabrasive particles are cemented under HPHT conditions.
U.S. Pat. No. 5,127,923 describes an abrasive compact with a substantially solid body that is provided from a mass of abrasive particles, which are bonded together on a particle-to-particle basis.
U.S. Pat. No. 5,151,107 describes superabrasive cutting elements, backed compacts and methods for their manufacture wherein metal-coated superabrasive particles are cemented under HPHT conditions.
U.S. Pat. No. 5,266,236 describes a method for making a thermally stable, dense, electrically conductive diamond compact.
U.S. Pat. No. 5,273,557 describes rotary drill bits and blanks which retain polycrystalline diamond or CBN compacts, but which do not suffer from disadvantages attendant by prior drill designs.
U.S. Pat. No. 5,304,342 describes a sintered product useful for abrasion- and impact-resistant tools and the like, comprising an iron-group metal binder and refractory metal carbide particles, e.g. tungsten carbide, formed in situ during sintering by the exothermic reaction of a carbide-forming refractory metal powder with a carbon source mixed therewith.
U.S. Pat. No. 5,351,772 describes a substantially polycrystalline diamond compact cutting element for drilling subterranean formations.
U.S. Pat. No. 5,370,195 describes a drill bit that has a means at one end for connecting the bit to a drill string and a plurality of inserts at the other end for crushing the rock to be drilled.
U.S. Pat. No. 5,435,403 describes a cutting element having a substantially planar table of superhard material mounted on a substrate or backing.
U.S. Pat. No. 5,590,729 describes a cutting element for a rotary drill bit for subterranean drilling, including a substantially planar table of superhard material having a cutting face and a cutting edge.
U.S. Pat. No. 5,605,198 describes a drill bit employing selective placement of cutting elements engineered to accommodate differing loads such as are experienced at different locations on the bit crown.
U.S. Pat. No. 5,769,176 describes a diamond sintered compact having a higher strength as well as more excellent heat resistance, breakage resistance and corrosion resistance.
U.S. Pat. No. 5,787,022 describes a drill bit employing selective placement of cutting elements engineered to accommodate differing loads such as are experienced at different locations on the bit crown.
U.S. Pat. No. 5,959,747 describes a drill bit employing selective placement of cutting elements engineered to accommodate differing loads such as are experienced at different locations on the bit crown.
U.S. Pat. No. 5,967,249 describes a cutter for use on a rotary-type drag bit for earth boring, comprising a substantially rectangular diamond table attached to a substrate.
U.S. Pat. No. 6,021,859 describes a drill bit employing selective placement of cutting elements engineered to accommodate differing loads such as are experienced at different locations on the bit crown.
U.S. Pat. No. 6,068,913 describes a PCD/PCBN tool and method for making the same that involves the use of an intermediate layer of polycrystalline material between a substrate and an outer working layer.
U.S. Pat. No. 6,245,312 B1 describes a superhard carbon material having a structure comprising structural elements, in the form of tetrahedrons, with groups of carbon atoms in their apices.
U.S. Pat. No. 6,315,065 B1 describes a cutter element for use in a drill bit, comprising a substrate and a plurality of layers thereon.
U.S. Pat. No. 6,401,844 B1 describes a cutter comprising a superabrasive volume that includes a cutting face portion extending transversely across a leading face of a supporting substrate and a contiguous jacket portion extending rearwardly over the supporting substrate along a portion of its side periphery.
U.S. Pat. No. 6,410,085 B1 describes a method of machining a polycrystalline diamond material that includes a matrix of interstices containing a catalyzing material and volume close to a working surface thereof substantially free of catalyzing material.
U.S. Pat. No. 6,435,058 B1 describes a method for use in designing rotary drill bits that comprises determining locations in which cutters are to be provided.
U.S. Pat. No. 6,443,248 B2 describes a cutter element for use in a drill bit, comprising a substrate and a plurality of layers thereon.
U.S. Pat. No. 6,481,511 B2 describes a rotary drill bit that includes cutters arranged in a series of concentric rings.
U.S. Pat. No. 6,544,308 B2 describes a polycrystalline diamond or diamond-like element with greatly improved wear resistance without loss of impact strength.
U.S. Pat. No. 6,562,462 B2 describes a polycrystalline diamond or diamond-like element with greatly improved wear resistance without loss of impact strength.
U.S. Pat. No. 6,585,064 B2 describes an earth boring drill bit with a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,589,640 B2 describes a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,592,985 B2 describes a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,601,662 B2 describes a polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,739,214 B2 describes a method of making an earth boring drill bit having a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,749,033 B2 describes a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,861,098 B2 describes a method for forming a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,861,137 B2 describes a method for manufacturing a polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.
U.S. Pat. No. 6,878,447 B2 describes a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength.